Daily Marijuana use linked to a decline in verbal memory in middle age

At the beginning of the study period in the 1980s, participants were 18 to 30 years old and more than 80 percent reported past marijuana use. Just 12 percent continued to use marijuana into middle age, according to the results in JAMA Internal Medicine.

Researchers found that as past years of marijuana use increased, verbal memory scores decreased. In practical terms, the results meant that for every additional five years of exposure, 50 percent of marijuana users would remember one less word from a list of 15 tested words. –Reuters